Flex fuel vehicle Vs. Gas?

Question

I know about E85 and the mpg when burning the lower energy fuel, but my question is if someone has a FFV are they loosing mpg if they only burn Gas in the engine? In other words if only using gasoline, is the FFV engine getting the same MPG as The non-flex fuel engine? Particularlly the F150. Thanks for the anwers.

Answer 1

should get the same "gas" mileage as as a non ffv when burning gasoline.

but since alcohol resists detonation an engine set up to run  ONLY on e85 could have a higher compression ratio & would get better mileage than one that has to run on gasoline too.

the best solution would be a variable compression engine that adjusted the compression to about 11.5 or 12 to 1 on e85 & lowered to 9.5 for gasoline. this can be done but such an engine would be much more expensive to build.

racing engines that run on pure alcohol run compression ratios of 13 to 1 & higher as pure alcohol has an octane of 110 or above

diesels run around 20 to 1 compression which is why they get much better fuel mileage than gasoline engines.

Answer 2

the only difference in flex fuel vehicles is the addition of a sensor in the fuel line that tells the computer how much alcohol is in the fuel when it reaches the sensor so the computer can adjust the fuel and timing setting to allow for best combustion. thus it doesnt matter if you have a flex fuel vehicle or not, the fuel economy will be the same, given the same driving style and the same type of fuel, for each vehicle.